IEC 63541:2025
(Main)Lithium tantalate and lithium niobate crystals for surface acoustic wave (SAW) device applications - Specifications and measuring methods
Lithium tantalate and lithium niobate crystals for surface acoustic wave (SAW) device applications - Specifications and measuring methods
IEC 63541:2025 applies to lithium tantalate (LT) and lithium niobate (LN) crystals for surface acoustic wave devices, including the as-grown crystals and lumbered crystals.
Cristaux de tantalate de lithium et de niobate de lithium pour applications utilisant des dispositifs à ondes acoustiques de surface (OAS) - Spécifications et méthodes de mesure
L'IEC 63541:2025 s'applique aux cristaux de tantalate de lithium (LT) et de niobate de lithium (LN) pour dispositifs à ondes acoustiques de surface, y compris les cristaux bruts et les cristaux localisés.
General Information
Standards Content (Sample)
IEC 63541 ®
Edition 1.0 2025-12
INTERNATIONAL
STANDARD
Lithium tantalate and lithium niobate crystals for surface acoustic wave (SAW)
device applications - Specifications and measuring methods
ICS 31.140 ISBN 978-2-8327-0946-7
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CONTENTS
FOREWORD. 3
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Requirements . 7
4.1 Material specification . 7
4.1.1 LN . 7
4.1.2 LT . 7
4.2 Requirements for as-grown crystal . 7
4.2.1 Specifications . 7
4.2.2 Macroscopic quality . 8
4.2.3 Single domain . 8
4.2.4 Curie temperature and tolerance . 8
4.2.5 Lattice parameter . 8
4.3 Requirements for lumbered crystal . 8
4.3.1 As-grown crystal for lumbered crystal . 8
4.3.2 Specifications . 8
5 Sampling and inspection . 9
5.1 General . 9
5.2 Sampling and inspection plan . 9
5.3 Determination of inspection results . 10
6 Test methods. 10
6.1 Test methods for as-grown crystal . 10
6.1.1 Diameter and cylinder length . 10
6.1.2 Macroscopic quality . 10
6.1.3 Single domain . 10
6.1.4 Curie temperature . 10
6.1.5 Lattice parameter . 10
6.2 Test methods for lumbered crystal . 11
6.2.1 Surface orientation . 11
6.2.2 Diameter . 11
6.2.3 Orientation of orientation flat . 11
6.2.4 Width of orientation flat . 11
6.2.5 Effective length . 11
6.2.6 Cylindricity . 11
6.2.7 Verticality . 11
7 Identification, labelling, packaging, delivery condition . 11
7.1 Packaging . 11
7.2 Labelling and identification . 11
7.3 Terms of delivery . 11
Annex A (normative) Measurement of single domain for LT and LN crystals . 12
A.1 General . 12
A.2 Measurement principle . 12
A.3 Measurement . 12
A.3.1 Scattered light path method . 12
A.3.2 Etching method . 13
A.3.3 Electromotive voltage method . 15
Annex B (normative) Measurement of Curie temperature . 17
B.1 General . 17
B.2 DTA method . 17
B.3 DSC method . 18
B.4 Dielectric constant method . 18
Annex C (normative) Measurement of lattice parameter (Bond method). 20
Annex D (normative) Measurement of cylindricity for LT and LN crystals . 22
D.1 General . 22
D.2 Measurement . 22
D.2.1 Equipment . 22
D.2.2 Measuring procedure . 22
D.2.3 Other instructions . 23
Annex E (normative) Measurement of verticality for LT and LN crystals . 24
E.1 General . 24
E.2 Measurement . 24
E.2.1 Equipment . 24
E.2.2 Measuring procedure . 24
Bibliography . 25
Figure 1 – Schematic diagram of lumbered crystal . 6
Figure 2 – Schematic diagram of verticality for lumbered crystal . 7
Figure A.1 – Schematic diagram of sample position . 14
Figure A.2 – Schematic diagram of measurement points . 14
Figure A.3 – Examples of 42°Y-X LT after etching . 14
Figure A.4 – Examples of 128°Y-X LN after etching . 15
Figure A.5 – Schematic diagram of waveform for single-domain crystals . 15
Figure A.6 – Schematic diagram of waveform for non-single-domain crystals . 16
Figure B.1 – Schematic of a DTA system . 17
Figure B.2 – Schematic of a DSC system . 18
Figure B.3 – Schematic of a dielectric constant measurement system . 19
Figure C.1 – The Bond method. 21
Figure D.1 – Measurement schematic diagram of cylindricity . 22
Figure E.1 – Measurement schematic diagram of verticality . 24
Table 1 – Typical specifications of as-grown crystal . 8
Table 2 – The centre value and tolerance of Curie temperature specification. 8
Table 3 – Typical specifications of lumbered crystal . 9
Table 4 – Sampling and inspection plan . 10
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Lithium tantalate and lithium niobate crystals
for surface acoustic wave (SAW) device applications -
Specifications and measuring methods
FOREWORD
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IEC 63541 has been prepared by IEC technical committee 49: Piezoelectric, dielectric and
electrostatic devices and associated materials for frequency control, selection and detection. It
is an International Standard.
The text of this International Standard is based on the following documents:
Draft Report on voting
49/1496/CDV 49/1517/RVC
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
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1 Scope
This document applies to lithium tantalate (LT) and lithium niobate (LN) crystals for surface
acoustic wave devices, including the as-grown crystals and lumbered crystals.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
– IEC Electropedia: available at https://www.electropedia.org/
– ISO Online browsing platform: available at https://www.iso.org/obp
3.1
as-grown crystal
synthetic crystal without any processing
3.2
crystal orientation
crystallization direction of the crystal
3.3
Curie temperature
T
c
temperature at which a ferroelectric material undergoes a structural phase transition to a state
where spontaneous polarization vanishes
Note 1 to entry: The Curie temperature is measured by differential thermal analysis (DTA), differential scanning
calorimetry (DSC), or dielectric measurement.
3.4
cylinder length
continuous geometric length which is greater than the minimum diameter of the corresponding
specification in as-grown crystal
3.5
cylindricity
difference between the maximum and minimum dimensions of any vertical section of lumbered
crystal
3.6
effective length
geometric length after the removal of internal defects and processing defects in the actual
length of lumbered crystal
3.7
lattice parameter
lattice constant
length of one unit cell along the major crystallographic axis
Note 1 to entry: The lattice parameter is measured by X-ray diffraction using the Bond method.
3.8
lithium niobate
LN
single crystal approximately described by the chemical formula LiNbO , grown by the
Czochralski (crystal pulling from melt) or other methods
3.9
lithium tantalate
LT
single crystal approximately described by the chemical formula LiTaO , grown by the
Czochralski (crystal pulling from melt) or other methods
3.10
lumbered crystal
synthetic crystal that has been processed flat by sawing, grinding, lapping, etc., to meet
specified dimensions and orientation as shown in Figure 1
Figure 1 – Schematic diagram of lumbered crystal
3.11
polarization process
electrical process used to establish a single domain crystal
3.12
single domain
ferroelectric crystal with uniform electric polarization throughout
3.13
surface orientation
crystallographic orientation of the axis perpendicular to the surface of the lumbered crystal
3.14
twin
two or more identical single crystals that are combined by the law of symmetrical plane or axis
Note 1 to entry: Twins exhibit symmetry that can be classified as reflection across a mirror plane (twin plane),
rotation around an axis (twin axis), or inversion through a point (twin centre).
Note 2 to entry: Optical twins (growth twins) and electrical twins (transformation twins) are the most relevant to
surface acoustic wave (SAW) wafers. Optical twins arise from defects related to growth. Electrical twins can result
from extreme conditions (temperature and pressure, for example) during processing.
3.15
verticality
angle between the surface and orientation flat of the lumbered crystal as shown in Figure 2
Figure 2 – Schematic diagram of verticality for lumbered crystal
4 Requirements
4.1 Material specification
4.1.1 LN
LN is a single domain material having a Curie temperature within the specified range.
4.1.2 LT
LT is a single domain material having a Curie temperature or lattice parameter within the
spec
...
IEC 63541 ®
Edition 1.0 2025-12
NORME
INTERNATIONALE
Cristaux de tantalate de lithium et de niobate de lithium pour applications
utilisant des dispositifs à ondes acoustiques de surface (OAS) - Spécifications
et méthodes de mesure
ICS 31.140 ISBN 978-2-8327-0946-7
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SOMMAIRE
AVANT-PROPOS . 3
1 Domaine d'application . 5
2 Références normatives . 5
3 Termes et définitions . 5
4 Exigences . 7
4.1 Spécifications des matériaux . 7
4.1.1 LN . 7
4.1.2 LT . 7
4.2 Exigences pour le cristal cultivé . 7
4.2.1 Spécifications . 7
4.2.2 Qualité macroscopique . 8
4.2.3 Domaine unique . 8
4.2.4 Température de Curie et tolérance . 8
4.2.5 Paramètre de réseau . 8
4.3 Exigences relatives au cristal lumbéré . 8
4.3.1 Cristal brut pour cristal lumbéré . 8
4.3.2 Spécifications . 8
5 Échantillonnage et contrôle . 9
5.1 Généralités . 9
5.2 Plan d"échantillonnage et de contrôle . 9
5.3 Détermination des résultats d'inspection . 10
6 Méthodes d'essais . 10
6.1 Méthodes d'essai pour les cristaux bruts . 10
6.1.1 Diamètre et longueur du cylindre . 10
6.1.2 Qualité macroscopique . 10
6.1.3 Domaine unique . 10
6.1.4 Température de Curie . 10
6.1.5 Paramètre de réseau . 10
6.2 Méthodes d'essai pour le cristal lumbéré . 11
6.2.1 Orientation de la surface . 11
6.2.2 Diamètre . 11
6.2.3 Orientation du plat d'orientation . 11
6.2.4 Largeur du plat d'orientation . 11
6.2.5 Longueur effective . 11
6.2.6 Cylindricité . 11
6.2.7 Verticalité . 11
7 Identification, étiquetage, emballage, conditions de livraison . 11
7.1 Emballage . 11
7.2 Étiquetage et identification . 11
7.3 Modalités de livraison . 11
Annexe A (normative) Mesure du domaine unique pour les cristaux LT et LN . 12
A.1 Généralités . 12
A.2 Principe de mesure . 12
A.3 Mesure . 12
A.3.1 Méthode du chemin de lumière diffusée . 12
A.3.2 Méthode de gravure . 13
A.3.3 Méthode par tension électromotrice . 15
Annexe B (normative) Mesure de la température de Curie . 17
B.1 Généralités . 17
B.2 Méthode d'analyse thermique différentielle . 17
B.3 Méthode DSC . 18
B.4 Méthode de la constante diélectrique . 18
Annexe C (normative) Mesure du paramètre de réseau (méthode de Bond) . 20
Annexe D (normative) Mesure de la cylindricité pour les cristaux LT et LN . 22
D.1 Généralités . 22
D.2 Mesure . 22
D.2.1 Appareil . 22
D.2.2 Procédure de mesure . 22
D.2.3 Autres instructions . 23
Annexe E (normative) Mesure de verticalité pour les cristaux LT et LN . 24
E.1 Généralités . 24
E.2 Mesure . 24
E.2.1 Appareil . 24
E.2.2 Procédure de mesure . 24
Bibliographie . 25
Figure 1 – Schéma de principe du cristal lumbéré . 6
Figure 2 – Schéma de verticalité du cristal lumbéré . 7
Figure A.1 – Schéma de principe de la position de l'échantillon . 14
Figure A.2 – Schéma de principe des points de mesure . 14
Figure A.3 – SExemples de 42°Y-X LT après gravure . 15
Figure A.4 – SExemples de LN 128°Y-X après gravure . 15
Figure A.5 – Schéma de forme d'onde des cristaux mono-domaine . 16
Figure A.6 – Schéma de forme d'onde pour les cristaux non mono-domaine . 16
Figure B.1 – Schéma d'un système DTA . 17
Figure B.2 – Schéma d'un système DSC . 18
Figure B.3 – Schéma d'un système de mesure de constante diélectrique . 19
Figure C.1 – Laméthode obligataire . 21
Figure D.1 – Schéma de principe de mesure de la cylindricité . 22
Figure E.1 – Schéma de principe de mesure de la verticalité . 24
Tableau 1 – Caractéristiques types du cristal cultivé . 8
Tableau 2 – La valeur centrale et la tolérance de la spécification de température de
Curie . 8
Tableau 3 – Spécifications types du cristal lumbéré . 9
Tableau 4 – Plan d'échantillonnage et de contrôle . 10
COMMISSION ÉLECTROTECHNIQUE INTERNATIONALE
____________
Cristaux de tantalate de lithium et de niobate de lithium pour applications
utilisant des dispositifs à ondes acoustiques de surface (OAS) -
Spécifications et méthodes de mesure
AVANT-PROPOS
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1 Domaine d'application
Le présent document s'applique aux cristaux de tantalate de lithium (LT) et de niobate de lithium
(LN) pour dispositifs à ondes acoustiques de surface, y compris les cristaux bruts et les cristaux
localisés.
2 Références normatives
Le présent document ne contient aucune référence normative.
3 Termes et définitions
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L'ISO et l'IEC tiennent à jour des bases de données terminologiques destinées à être utilisées
en normalisation, consultables aux adresses suivantes:
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– ISO Online browsing platform: disponible à l'adresse https://www.iso.org/obp
3.1
cristal cultivé
cristal synthétique sans traitement
3.2
orientation du cristal
direction de cristallisation du cristal
3.3
Température de Curie
T
c
température à laquelle un matériau ferroélectrique subit une transition de phase structurelle
vers un état dans lequel la polarisation spontanée disparaît
Note 1 à l'article: La température de Curie est mesurée par analyse thermique différentielle (DTA, Differential
Thermal Analysis), calorimétrie différentielle à balayage (DSC, Differential Scanning Calorimetry) ou mesure
diélectrique.
3.4
longueur du cylindre
longueur géométrique continue supérieure au diamètre minimal de la spécification
correspondante dans le cristal obtenu
3.5
cylindricité
différence entre les dimensions maximale et minimale d'une quelconque section verticale de
cristal localisé
3.6
longueur effective
longueur géométrique après élimination des défauts internes et des défauts de traitement dans
la longueur réelle du cristal lumbéré
3.7
paramètre du réseau cristallin
constante du réseau cristallin
longueur d'une cellule unitaire le long de l'axe cristallographique principal
Note 1 à l'article: Le paramètre du réseau cristallin est mesuré par diffraction de rayons X par la méthode de Bond.
3.8
niobate de lithium
LN
monocristal décrit approximativement par la formule chimique LiNbO , développé par la
méthode de Czochralski (tirage du cristal fondu) ou par d'autres méthodes
Note 1 à l'article: L'abréviation "LN" est dérivée du terme anglais développé correspondant "lithium niobate".
3.9
tantalate de lithium
LT
monocristal décrit approximativement par la formule chimique LiTaO3, développé par la
méthode de Czochralski (tirage du cristal fondu) ou par d'autres méthodes
Note 1 à l'article: L'abréviation "LT" est dérivée du terme anglais développé correspondant "lithium tantalate".
3.10
cristal localisé
cristal synthétique traité à plat par sciage, meulage, rodage, etc., afin de respecter les
dimensions et l'orientation spécifiées, comme représenté à la Figure 1
Figure 1 – Schéma de principe du cristal lumbéré
3.11
processus de polarisation
processus électrique utilisé pour établir un cristal de domaine unique
3.12
domaine unique
cristal ferroélectrique avec polarisation électrique entièrement uniforme
3.13
orientation de la surface
orientation cristallographique de l'axe perpendiculaire à la surface du cristal localisé
3.14
cristal jumeau
deux ou plusieurs monocristaux identiques combinés par la loi du plan ou de l'axe symétrique
Note 1 à l'article: Les jumeaux présentent une symétrie qui peut être classée comme une réflexion à travers un
plan miroir (plan jumelé), une rotation autour d'un axe (axe jumelé) ou une inversion à travers un point
(centre jumelé).
Note 2 à l'article: Les jumeaux optiques (jumeaux de croissance) et les jumeaux électriques (jumeaux de
transformation) sont les plus importants pour les tranches à ondes acoustiques de surface (OAS). Les jumeaux
optiques proviennent de défauts associés à la croissance. Les jumeaux électriques peuvent résulter de conditions
extrêmes (température et pression, par exemple) pendant le traitement.
3.15
verticalité
angle entre la surface et le plat d'orientation du cristal lumbéré comme représenté à la Figure 2
Figure 2 – Schéma de verticalité du cristal lumbéré
4 Exigences
4.1 Spécifications des matériaux
4.1.1 LN
Le LN est un matériau de domaine unique ayant une température de Curie dans la plage
spécifiée.
4.1.2 LT
LT est un matériau à domaine unique ayant une température de Curie ou un paramètre de
réseau compris dans la plage spécifiée.
4.2 Exigences pour le cristal cultivé
4.2.1 Spécifications
Des spécifications types du cristal cultivé sont représentées dans le Tableau 1.
Tableau 1 – Caractéristiques types du cristal cultivé
Matériau Orientat
...
IEC 63541 ®
Edition 1.0 2025-12
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Lithium tantalate and lithium niobate crystals for surface acoustic wave (SAW)
device applications - Specifications and measuring methods
Cristaux de tantalate de lithium et de niobate de lithium pour applications
utilisant des dispositifs à ondes acoustiques de surface (OAS) - Spécifications
et méthodes de mesure
ICS 31.140 ISBN 978-2-8327-0946-7
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CONTENTS
FOREWORD. 3
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Requirements . 7
4.1 Material specification . 7
4.1.1 LN . 7
4.1.2 LT . 7
4.2 Requirements for as-grown crystal . 7
4.2.1 Specifications . 7
4.2.2 Macroscopic quality . 8
4.2.3 Single domain . 8
4.2.4 Curie temperature and tolerance . 8
4.2.5 Lattice parameter . 8
4.3 Requirements for lumbered crystal . 8
4.3.1 As-grown crystal for lumbered crystal . 8
4.3.2 Specifications . 8
5 Sampling and inspection . 9
5.1 General . 9
5.2 Sampling and inspection plan . 9
5.3 Determination of inspection results . 10
6 Test methods. 10
6.1 Test methods for as-grown crystal . 10
6.1.1 Diameter and cylinder length . 10
6.1.2 Macroscopic quality . 10
6.1.3 Single domain . 10
6.1.4 Curie temperature . 10
6.1.5 Lattice parameter . 10
6.2 Test methods for lumbered crystal . 11
6.2.1 Surface orientation . 11
6.2.2 Diameter . 11
6.2.3 Orientation of orientation flat . 11
6.2.4 Width of orientation flat . 11
6.2.5 Effective length . 11
6.2.6 Cylindricity . 11
6.2.7 Verticality . 11
7 Identification, labelling, packaging, delivery condition . 11
7.1 Packaging . 11
7.2 Labelling and identification . 11
7.3 Terms of delivery . 11
Annex A (normative) Measurement of single domain for LT and LN crystals . 12
A.1 General . 12
A.2 Measurement principle . 12
A.3 Measurement . 12
A.3.1 Scattered light path method . 12
A.3.2 Etching method . 13
A.3.3 Electromotive voltage method . 15
Annex B (normative) Measurement of Curie temperature . 17
B.1 General . 17
B.2 DTA method . 17
B.3 DSC method . 18
B.4 Dielectric constant method . 18
Annex C (normative) Measurement of lattice parameter (Bond method). 20
Annex D (normative) Measurement of cylindricity for LT and LN crystals . 22
D.1 General . 22
D.2 Measurement . 22
D.2.1 Equipment . 22
D.2.2 Measuring procedure . 22
D.2.3 Other instructions . 23
Annex E (normative) Measurement of verticality for LT and LN crystals . 24
E.1 General . 24
E.2 Measurement . 24
E.2.1 Equipment . 24
E.2.2 Measuring procedure . 24
Bibliography . 25
Figure 1 – Schematic diagram of lumbered crystal . 6
Figure 2 – Schematic diagram of verticality for lumbered crystal . 7
Figure A.1 – Schematic diagram of sample position . 14
Figure A.2 – Schematic diagram of measurement points . 14
Figure A.3 – Examples of 42°Y-X LT after etching . 14
Figure A.4 – Examples of 128°Y-X LN after etching . 15
Figure A.5 – Schematic diagram of waveform for single-domain crystals . 15
Figure A.6 – Schematic diagram of waveform for non-single-domain crystals . 16
Figure B.1 – Schematic of a DTA system . 17
Figure B.2 – Schematic of a DSC system . 18
Figure B.3 – Schematic of a dielectric constant measurement system . 19
Figure C.1 – The Bond method. 21
Figure D.1 – Measurement schematic diagram of cylindricity . 22
Figure E.1 – Measurement schematic diagram of verticality . 24
Table 1 – Typical specifications of as-grown crystal . 8
Table 2 – The centre value and tolerance of Curie temperature specification. 8
Table 3 – Typical specifications of lumbered crystal . 9
Table 4 – Sampling and inspection plan . 10
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Lithium tantalate and lithium niobate crystals
for surface acoustic wave (SAW) device applications -
Specifications and measuring methods
FOREWORD
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IEC 63541 has been prepared by IEC technical committee 49: Piezoelectric, dielectric and
electrostatic devices and associated materials for frequency control, selection and detection. It
is an International Standard.
The text of this International Standard is based on the following documents:
Draft Report on voting
49/1496/CDV 49/1517/RVC
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
– reconfirmed,
– withdrawn, or
– revised.
1 Scope
This document applies to lithium tantalate (LT) and lithium niobate (LN) crystals for surface
acoustic wave devices, including the as-grown crystals and lumbered crystals.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
– IEC Electropedia: available at https://www.electropedia.org/
– ISO Online browsing platform: available at https://www.iso.org/obp
3.1
as-grown crystal
synthetic crystal without any processing
3.2
crystal orientation
crystallization direction of the crystal
3.3
Curie temperature
T
c
temperature at which a ferroelectric material undergoes a structural phase transition to a state
where spontaneous polarization vanishes
Note 1 to entry: The Curie temperature is measured by differential thermal analysis (DTA), differential scanning
calorimetry (DSC), or dielectric measurement.
3.4
cylinder length
continuous geometric length which is greater than the minimum diameter of the corresponding
specification in as-grown crystal
3.5
cylindricity
difference between the maximum and minimum dimensions of any vertical section of lumbered
crystal
3.6
effective length
geometric length after the removal of internal defects and processing defects in the actual
length of lumbered crystal
3.7
lattice parameter
lattice constant
length of one unit cell along the major crystallographic axis
Note 1 to entry: The lattice parameter is measured by X-ray diffraction using the Bond method.
3.8
lithium niobate
LN
single crystal approximately described by the chemical formula LiNbO , grown by the
Czochralski (crystal pulling from melt) or other methods
3.9
lithium tantalate
LT
single crystal approximately described by the chemical formula LiTaO , grown by the
Czochralski (crystal pulling from melt) or other methods
3.10
lumbered crystal
synthetic crystal that has been processed flat by sawing, grinding, lapping, etc., to meet
specified dimensions and orientation as shown in Figure 1
Figure 1 – Schematic diagram of lumbered crystal
3.11
polarization process
electrical process used to establish a single domain crystal
3.12
single domain
ferroelectric crystal with uniform electric polarization throughout
3.13
surface orientation
crystallographic orientation of the axis perpendicular to the surface of the lumbered crystal
3.14
twin
two or more identical single crystals that are combined by the law of symmetrical plane or axis
Note 1 to entry: Twins exhibit symmetry that can be classified as reflection across a mirror plane (twin plane),
rotation around an axis (twin axis), or inversion through a point (twin centre).
Note 2 to entry: Optical twins (growth twins) and electrical twins (transformation twins) are the most relevant to
surface acoustic wave (SAW) wafers. Optical twins arise from defects related to growth. Electrical twins can result
from extreme conditions (temperature and pressure, for example) during processing.
3.15
verticality
angle between the surface and orientation flat of the lumbered crystal as shown in Figure 2
Figure 2 – Schematic diagram of verticality for lumbered crystal
4 Requirements
4.1 Material specification
4.1.1 LN
LN is a single domain material having a Curie temperature within the specified range.
4.1.2 LT
LT is a single domain material having a Curie temperature or lattice parameter within the
specified range.
4.2 Requirements for as-grown crystal
4.2.1 Specifications
Typical specifications of the as-grown crystal are shown in Table 1.
Table 1 – Typical specifications of as-grown crystal
Material Crystal orientation Diameter Cylinder length
mm mm
LN Y axis, Z axis, 15°Y, 64°Y, 128°Y, etc. ≥ 78 ≥ 60
(3") (3")
≥ 104 ≥ 55
(4") (4")
LT X axis, Z axis, 36°Y, 38°Y, 42°Y, etc. ≥ 130 ≥ 50
(5") (5")
≥ 155 ≥ 45
(6") (6")
4.2.2 Macroscopic quality
The as-grown crystal is visually transparent, without cracks, inclusions, twins.
4.2.3 Single domain
The ferroelectric domains direction of the as-grown crystal after polarization process should be
in the same direction.
4.2.4 Curie temperature and tolerance
The centre value and tolerance of Curie temperature specification are specified in Table 2, or
are as agreed upon by the user and the supplier.
Table 2 – The centre value and tolerance of Curie temperature specification
Material The centre value Tolerance
°C °C
A B C
LN 1 133 to 1 145 ±1 ±2 ±3
LT 598 to 608 ±1 ±2 ±3
4.2.5 Lattice parameter
LT 0,515 40 nm ± 0,000 02 nm for α-axis measured at 25 °C.
NOTE Alternatively, the Curie temperature of LT can be specified in 4.2.4.
4.3 Requirements for lumbered crystal
4.3.1 As-grown crystal for lumbered crystal
The as-grown crystal used for manufacturing lumbered crystal shall comply with the
requirements of 4.2.
4.3.2 Specifications
Typical specifications of lumbered crystal are specified in Table 3.
Table 3 – Typical specifications of lumbered crystal
Surface
Tolerance
Tolerance Width of
orientation Effective
of Cylindricity
c
Material of surface Diameter orientation
Verticality
b,c c
and
orientation
length
orientation flat
a
flat
propagation
' mm ' mm mm mm °
128° Y-X 76,5 + 0,2 22,0 ± 2,0 ≥ 45
LN Y-Z (3") (3") (3")
100,3 + 0,2 32,5 ± 2,0 ≥ 45
64° Y- X
(4") (4") (4")
X- 112° Y
± 15 ±15 ≤ 0,1 90 ± 0,05
125,3 + 0,2 42,5 ± 2,0 ≥ 30
36° Y-X
LT (5") (5") (5")
150,3 + 0,2 47,5 ± 2,0 ≥ 30
42° Y-X
(6") (6") (6")
a
The "propagation" corresponds to the "SAW propagation direction" specified in IEC 62276:2025, 3.3.6.
b
The effective length of the lumbered crystal shall be not less than 80 % of the total length.
c
The "effective length", "cylindricity", "verticality" are optional technical indicators that can be selected when
required.
5 Sampling and inspection
5.1 General
The quality of as-grown crystal and lumbered crystal shall comply with this document (or
contract), and the quality certificate shall be filled out. The sampling plan shall be agreed upon
by the user and the supplier, and the inspection method shall satisfy the requirements of quality
assurance criteria. The as-grown crystal and lumbered crystal shall be submitted for acceptance
in batches, and the constitution of the batch shall be agreed upon by the user and the supplier.
5.2 Sampling and inspection plan
Appropriate statistical methods shall be applied to determine adequate sample size and
acceptance criteria for the considered lot size. In the absence of more detailed statistical
analysis, inspection of whole population can be carried out, and the sampling plan is shown in
Table 4.
Table 4 – Sampling and inspection plan
Type Sampling items Sampling plan Requirements Test methods
Diameter 4.2.1 6.1.1
Cylinder length 4.2.1 6.1.1
Macroscopic quality 4.2.2 6.1.2
As-grown crystal
Single domain 4.2.3 6.1.3
Curie temperature 4.2.4 6.1.4
Inspection of whole
Lattice parameter 4.2.5 6.1.5
population
Tolerance of surface orientation 4.3.2 6.2.1
(except etching method
Diameter 4.3.2 6.2.2
of single domain)
Tolerance of orientation flat 4.3.2 6.2.3
Lumbered crystal Width of orientation flat 4.3.2 6.2.4
Effective length 4.3.2 6.2.5
Cylindricity 4.3.2 6.2.6
Verticality 4.3.2 6.2.7
5.3 Determination of inspection results
When inspecting as-grown crystal and lumbered crystal, if any sampling item is unqualified, this
inspection batch is judged to be unqualified.
6 Test methods
6.1 Test methods for as-grown crystal
6.1.1 Diameter and cylinder length
The diameter and cylinder length of the equal diameter part in the as-grown crystal are
measured with the measuring tool that meets the accuracy requirements.
6.1.2 Macroscopic quality
The macroscopic quality of the as-grown crystal is visually checked by laser or other high-
intensity light in a dark room.
6.1.3 Single domain
The single-domain of as-grown crystal is measured in accordance with Annex A.
6.1.4 Curie temperature
The Curie temperature of as-grown crystal may be determined by either calorimetric or dielectric
measurement methods (see Annex B).
6.1.5 Lattice parameter
The crystal lattice parameter may be determined by XRD (see Annex C).
6.2 Test methods for lumbered crystal
6.2.1 Surface orientation
The surface orientation of lumbered crystal is measured by referring to IEC 62276:2025, 8.3.
6.2.2 Diameter
The diameter of lumbered crystal is measured with the measuring tool that meets the accuracy
requirements.
6.2.3 Orientation of orientation flat
The orientation of orientation flat for lumbered crystal is measured by referring to
IEC 62276:2025, 8.4.
6.2.4 Width of orientation flat
The width of orientation flat for lumbered crystal is measured with the measuring tool that meets
the accuracy requirements.
6.2.5 Effective length
The effective length of lumbered crystal is measured with the measuring tool that meets the
accuracy requirements.
6.2.6 Cylindricity
The cylindricity of lumbered crystal is measured in accordance with Annex D.
6.2.7 Verticality
The verticality between the surface and orientation flat of the lumbered crystal is measured with
a digital display angle ruler, detailed measurement is in accordance with Annex E.
7 Identification, labelling, packaging, delivery condition
7.1 Packaging
The as-grown crystal and lumbered crystal shall be packaged by the supplier so as to avoid
contamination or damage during shipping or storage. Special packaging requirements shall be
subject to agreement between the user and the supplier.
7.2 Labelling and identification
All containers of as-grown crystal and lumbered crystal shall include labels with the following
information:
a) supplier's name or trade mark;
b) material type;
c) crystal orientation of as-grown crystal, or surface orientation and propagation of lumbered
crystal;
d) manufacturing lot number;
e) quantity.
7.3 Terms of delivery
Terms of delivery are negotiated between the user and the supplier.
Annex A
(normative)
Measurement of single domain for LT and LN crystals
A.1 General
Annex A specifies the measurement of the single domain for LT and LN crystals grown by the
Czochralski method, including scattered light path method, etching method and electromotive
voltage method.
A.2 Measurement principle
In the scattered light path method, because the domain walls of LT and LN crystals have strong
light scattering effect on the laser beam, there are obvious green scattering light paths in the
multi-domain LT and LN crystals when irradiated with laser beam. Through single domain
treatment, the domain walls disappear and the scattering effect cannot happen under the laser
beam, so the domain structure of the crystal can be judged according to the scattering of the
laser in the crystals.
In the etching method, through the single-domain treatment, multi-domain crystals will change
to single-domain crystals with positive polarization at one end and negative polarization at the
other end. Under etching conditions, the etching rate of positive polarization end is slower than
that of negative polarization end, and this difference leads to the formation of a different etching
pattern on the polarization surfaces. Therefore, the domain structure of the crystal can be
determined based on the etching pattern of polarization surfaces.
The electromotive voltage method uses the piezoelectric effect of LT and LN single crystals to
judge whether the crystal is single domain by the voltage waveform.
A.3 Measurement
A.3.1 Scattered light path method
A.3.1.1 Equipment
The equipment consists of the following:
a) laser sensor, 100 mW;
b) darkroom.
A.3.1.2 Sample
The sample for scattered light path method is as-grown crystal.
A.3.1.3 Measuring procedure
The measurement procedure consists of the following steps:
a) turn on the laser sensor in the darkroom to generate a green laser beam;
b) the crystal is placed in the position where the laser beam passes through. It is carefully
moved, so that the laser beam gradually passes through each part of the crystal; or the laser
beam is perpendicular to the pulling axis to illuminate the crystal and the crystal rotates
along the pulling axis. Finally, the light path scattering situation in the crystal is observed.
A.3.1.4 Result judgment
If obvious green scattered light path is observed inside the crystal, the structure of the crystal
is multi-domain. If no scattered light path or weak scattered light path is observed inside the
crystal, the structure of the crystal is single domain.
A.3.2 Etching method
A.3.2.1 Etching solution
The etching solution consists of the following components:
a) nitric acid solution (HNO ): (a mass fraction of 65 %);
b) hydrofluoric acid solution (HF): (a mass fraction of 40 %);
c) HNO : HF = 1:1 (volume ratio).
A.3.2.2 Equipment
The major equipment specifications are as follows:
a) inner circle cutting machine;
b) metallographic microscope;
c) etching-resistant container;
d) platinum crucible;
e) electric furnace: 1 kW;
f) etching-resistant heater.
A.3.2.3 Sampling
After the single domain treatment, 1,5 mm thick wafer is cut from the two ends of the crystal.
The surfaces are then polished to make them without bright spots and mechanical scratches.
A.3.2.4 Sample preparation
Place the sample in the etching-resistant container, inject the etching solution until the sample
is immersed, and heat it to 85 °C to 90 °C. The etching time of LT wafer is 1 h, and the etching
time of LN wafer is 15 min to 30 min.
A.3.2.5 Cleaning
The etching solution adsorbed on the sample is fully washed by clean water and dried with
mirror wiping paper.
A.3.2.6 Measuring procedure
The measurement procedure consists of the following steps:
a) the sample is observed under the metallographic microscope;
b) the microscope magnification is set accurately (magnification for LT is 200 times,
magnification for LN is 100 times), the schematic diagram of the sample position is shown
in Figure A.1. Five measurement points on the sample are selected as shown in Figure A.2;
c) when measuring, ensure that the orientation flat of sample is relatively parallel to the edge
of the test platform when it is moved.
Figure A.1 – Schematic diagram of sample position
Figure A.2 – Schematic diagram of measurement points
A.3.2.7 Typical etching pattern examples
Typical etching pattern examples are shown in Figure A.3 and Figure A.4.
a) Positive polarization surface b) Negative polarization surface
Figure A.3 – Examples of 42°Y-X LT after etching
a) Positive polarization surface b) Negative polarization surface
Figure A.4 – Examples of 128°Y-X LN after etching
A.3.3 Electromotive voltage method
A.3.3.1 Equipment
The equipment is the digital oscilloscope with waveform storage function and resistance probes
for testing.
A.3.3.2 Measuring procedure
The measurement procedure consists of the following steps:
a) prepare the resistance probe;
b) place either end of the as-grown crystal on the resistance probe of the digital oscilloscope;
c) tap the other end or the side of the as-grown crystal with the resistance probe to generate
voltage;
d) view the waveform displayed on the oscilloscope.
A.3.3.3 Result judgment
If the oscilloscope displays any waveform illustrated in Figure A.5, it indicates that the crystal
is single domain. If the oscilloscope displays no waveform, it indicates that the crystal is not
single domain (see Figure A.6).
a) Positive polarization end at the top b) Negative polarization end at the top
Figure A.5 – Schematic diagram of waveform for single-domain crystals
Figure A.6 – Schematic diagram of waveform for non-single-domain crystals
Annex B
(normative)
Measurement of Curie temperature
B.1 General
Curie temperature (T ) is determined by destructive methods that are performed on LT and LN
c
single crystals, including DTA (differential thermal analysis), DSC (differential scanning
calorimetry), or dielectric constant methods. Which measuring methods should be used
depends on the agreement between the user and the supplier.
B.2 DTA method
The DTA method is based on the endothermic or exothermic reaction observed when a single
crystal transitions from the ferroelectric to paraelectric state. Typically, the sample and a
reference material are symmetrically positioned in an oven (see Figure B.1) and heated at a
constant rate, while recording the temperature difference between the materials. Alumina
(α-Al O ) is often used as the reference when running DTA experiments on LN or LT. Heat is
2 3
released at the LN or LT sample, passes upward through the phase transition temperature, and
the temperature profile relative to the alumina reference is recorded. The Curie temperature T
c
is defined as the temperature at which the temperature difference arises.
Figure B.1 – Schematic of a DTA system
B.3 DSC method
The DSC method is a technique that measures the relationship between the heat flow rate or
heating power input to the sample and reference material with respect to temperature or time
under programmed temperature control. The data curve obtained has the vertical axis as the
heat flow rate or heat flow, with units of mW (mJ/s), and the horizontal axis as temperature or
time. The instrumentation of DSC and DTA is similar, with the difference being that there are
two sets of compensating heating wires under the sample and reference material containers. In
Figure B.2, when there is a temperature difference ∆T between the sample and reference
material during the heating process, the current flowing into the compensating heating wires
changes due to the differential heat amplification circuit and differential heat compensation
amplifier. When the sample absorbs heat, the compensating amplifier immediately increases
the current on the sample side; conversely, when the sample releases heat, it increases the
current on the reference material side until the heat balance is achieved and the temperature
difference ∆T disappears.
Figure B.2 – Schematic of a DSC system
B.4 Dielectric constant method
The dielectric constant method relies upon observing the dielectric constant along the polar
Z-axis of a ferroelectric crystal. The dielectric constant maximum is found to occur at the phase
transition temperature. Since the dielectric constant, and thus the capacitance, for a given
sample are a function of temperature only, the heating or cooling rates can be chosen to be
small enough so as to minimize thermal hysteresis. In Figure B.3, the electrode of Pt or Ag-Pd
is placed on the sample so that the electric field runs along the polar Z-axis. While scanning
the temperature across the phase transition, the capacitance of the sample is measured by the
LCR-meter. The temperature at which the peak capacitance is observed corresponds to the
Curie temperature T .
c
Figure B.3 – Schematic of a dielectric constant measurement system
Annex C
(normative)
Measurement of lattice parameter (Bond method)
As the chemical composition of a crystal changes, so do the SAW velocities and lattice
–4
parameters. In order to control the SAW velocity to within one part per ten thousand (10 ), the
–5
lattice parameters shall be controlled within 10 . The measurement method in turn shall
–6
achieve part per million (10 ) resolution.
X-ray diffraction is used to measure lattice parameters. The method is based on Bragg's law as
shown in Formula (C.1):
2d sinθ=nλ (C.1)
where
d is the lattice spacing,
θ is the Bragg angle,
λ is the X-ray wavelength, and
n is the integer diffraction order.
λ
If is given, d and lattice parameters are determined by measuring θ. A sensitivity analysis is
shown in Formula (C.2):
∆d
=−cotθ×∆θ (C.2)
d
where ∆θ shall be measured correctly to within an arc second in order to measure ∆d/d on a
–6 –7
scale of 10 to 10 . In 1960, Dr. Bond developed a method to measure the value of the lattice
parameters precisely.
In the Bond method, two measurements are made, (i.e. the 'plus-side' and 'minus-side'), located
symmetrically around the same lattice face. The values Ω and Ω from the peaks of rocking
1 2
curve are determined as Figure C.1 shows and θ is calculated according to Formula (C.3):
θ πω−−ω (C.3)
( )
This method eliminates off-centre error plus absorption, and zero error is theoretically
eliminated as well. Note that temperature, refraction, divergence and Lorentz-polarization
corrections should be taken into account.
=
For the case of LiTaO , the Miller index (60-60) was evaluated by the Bond method. The α-axis
lattice parameter is calculated according to Formula (C.4):
α= 6d
(C.4)
60,0
After applying various corrections, the lattice parameter of LiTaO is determined to an accuracy
–6 –7
of 10 to 10 .
Figure C.1 – The Bond method
Annex D
(normative)
Measurement of cylindricity for LT and LN crystals
D.1 General
Annex D specifies the measurement of cylindricity for LT and LN lumbered crystals through the
three-point method.
D.2 Measurement
D.2.1 Equipment
The equipment consists of the following:
a) flat plate;
b) V-shaped block, with angle α = 120°;
c) measuring rack with indicator.
D.2.2 Measuring procedure
The measurement procedure consists of the following steps:
a) reset the indicator to zero, then the lumbered crystal is placed inside the V-shaped block on
the flat plate (the length of the V-shaped block should be greater than that of the crystal),
and the test probe contacts the surface of the crystal, the measurement schematic diagram
of cylindricity is shown in Figure D.1;
b) after turning the crystal for one rotation, the maximum and minimum dimension values are
read out from the indicator for one cross section of the crystal, then that for cross sections
in two ends of lumbered crystal are respectively measured according to the need; finally the
difference between the maximum and the minimum of all the dimension values is taken as
cylindricity.
α is the angle of V-shaped block.
Figure D.1 – Measurement schematic diagram of cylindricity
D.2.3 Other instructions
Further guidance is provided as follows:
a) the test rotates slowly and evenly without pulsation.
b) during measurement of cylindricity, the d
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