IEC TS 61994-4-1:2018

IEC TS 61994-4-1 ®
Edition 3.0 2018-11
REDLINE VERSION
TECHNICAL
SPECIFICATION
colour
inside
Piezoelectric, dielectric and electrostatic devices and associated materials for
frequency control, selection and detection – Glossary –
Part 4-1: Piezoelectric materials – Synthetic quartz crystal

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IEC TS 61994-4-1 ®
Edition 3.0 2018-11
REDLINE VERSION
TECHNICAL
SPECIFICATION
colour
inside
Piezoelectric, dielectric and electrostatic devices and associated materials for

frequency control, selection and detection – Glossary –

Part 4-1: Piezoelectric materials – Synthetic quartz crystal

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 01.040.31; 31.140 ISBN 978-2-8322-6281-8

– 2 – IEC TS 61994-4-1:2018 RLV © IEC 2018
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
Bibliography . 13

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
PIEZOELECTRIC, DIELECTRIC AND ELECTROSTATIC DEVICES
AND ASSOCIATED MATERIALS FOR FREQUENCY CONTROL, SELECTION
AND DETECTION – GLOSSARY –
Part 4-1: Piezoelectric materials – Synthetic quartz crystal

FOREWORD
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– 4 – IEC TS 61994-4-1:2018 RLV © IEC 2018
The main task of IEC technical committees is to prepare International Standards. In exceptional
circumstances, a technical committee may propose the publication of a technical specification
when
• the required support cannot be obtained for the publication of an International Standard,
despite repeated efforts, or
• the subject is still under technical development or where, for any other reason, there is the
future but no immediate possibility of an agreement on an International Standard.
Technical specifications are subject to review within three years of publication to decide whether
they can be transformed into International Standards.
IEC TS 61944-4-1, which is a technical specification, has been prepared by IEC technical
committee 49: Piezoelectric, dielectric and electrostatic devices and associated materials for
frequency control, selection and detection.
This third edition of IEC 61994-4-1 cancels and replaces the second edition published in 2007.
This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) The new terms and definitions given in IEC 60758:2016 have been taken into account;
b) The general title has been changed according to the change in the title of TC 49 in 2009.
The text of this technical specification is based on the following documents:
Enquiry draft Report on voting
49/1282/DTS 49/1286/RVDTS
Full information on the voting for the approval of this technical specification can be found in the
report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 61994 series, published under the general title Piezoelectric,
dielectric and electrostatic devices and associated materials for frequency control, selection and
detection – Glossary, can be found on the IEC website.
Future standards in this series will carry the new general title as cited above. Titles of existing
standards in this series will be updated at the time of the next edition.
The committee has decided that the contents of this publication will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific publication. At this date, the publication will be
• transformed into an International standard,
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The “colour inside” logo on the cover page of this publication indicates
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PIEZOELECTRIC, DIELECTRIC AND ELECTROSTATIC DEVICES
AND ASSOCIATED MATERIALS FOR FREQUENCY CONTROL, SELECTION
AND DETECTION – GLOSSARY –
Part 4-1: Piezoelectric materials – Synthetic quartz crystal

1 Scope
This part of IEC 61994 gives the terms and definition for synthetic quartz single crystals
representing the state of the art, which are intended for manufacturing piezoelectric and optical
elements for frequency control and selection.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60050(561):1991, International Electrotechnical Vocabulary (lEV) – Chapter 561:
Piezoelectric devices for frequency control and selection
IEC 60758:2004, Synthetic quartz crystal – Specifications and guide to the use
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 terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
AT-cut plate
rotated Y-cut crystal plate oriented at an angle of about +35° around the X-axis or about −3°
from the z (minor rhombohedral)-face
[SOURCE: IEC 60758:2016, 3.7.2 3.11, modified – the reference to Figure 3 has been
removed.]
3.2
as-grown Y-bar
crystals which are produced using seeds with the largest dimension grown by using long stick
seed in the Y-direction
[SOURCE: IEC 60758:2016, 3.2.2 3.4]

– 6 – IEC TS 61994-4-1:2018 RLV © IEC 2018
3.3
as-grown Z-bar
as-grown Y-bar crystals in which the Z-grown sector is much larger than the X-growth sector.
The relative size of the growth sector is controlled by the X-dimension of the seed
crystals which are grown by using Z-cut seed
[SOURCE: IEC 60758:2016, 3.2.3 modified 3.5]
3.4
as-grown synthetic quartz crystal
single crystal quartz grown hydrothermally. "As-grown" refers to the state of processing and
indicates a state prior to mechanical fabrication
state of synthetic quartz crystal prior to grinding or cutting
[SOURCE: IEC 60758:2016, 3.2.1 modified 3.3]
3.5
autoclave
vessel for the high-pressure and high-temperature condition required for growth of a synthetic
quartz crystal
[SOURCE: IEC 60758:2016, 3.15 3.26]
3.6
dimensions
dimensions pertaining to growth on Z-cut seed rotated less than 20° from the Y-axis
[SOURCE: IEC 60758:2016, 3.16]
3.7
dislocations
linear defects in the crystal due to misplaced planes of atoms
[SOURCE: IEC 60758:2016, 3.13 3.25]
3.8
dopant
any additive used in the growth process which may change the crystal habit, chemical
composition, physical or electrical properties of the synthetic quartz batch
[SOURCE: IEC 60758:2016, 3.10 3.22]
3.9
effective Z-dimension
as-grown effective Z dimension which is defined as the minimum measure in the Z (θ = 0°) or Z'
direction in usable Y or Y' area of an as-grown crystals and described by Z
eff
[SOURCE: IEC 60758:2016, 3.8.1.1 3.17 modified – The definition has been shortened and the
reference to Figure 2 has been removed.]
3.9
electrical twins
quartz crystal in which regions with a common Z-axis exist, showing a polarity reversal of the
electrical X-axis
[IEC 60758, 3.17]
3.10
etch channel
roughly cylindrical void that is present along the dislocation line after etching a test wafer
prepared from a quartz crystal
[SOURCE: IEC 60758:2016, 3.14 3.21]
3.11
gross dimensions
maximum dimensions along the X-, Y- or Y’- and Z- or Z’-axes measured along the X-, Y'- and
Z'-axes
[IEC 60758, 3.8.1]
3.11
growth band
contrasting density band that can be observed in the Y-cut crystal by Schlieren and similar
optical method
[SOURCE: IEC 60758:2016, 3.35, modified – The four notes to entry have been removed.]
3.12
growth zones
regions of a synthetic quartz crystal resulting from growth along different crystallographic
directions
[SOURCE: IEC 60758:2016, 3.5 3.8, modified – The reference to Figure 2 has been removed.]
3.13
hydrothermal crystal growth
literally crystal growth in the presence of water, elevated temperatures and pressures by a
crystal growth process believed to proceed geologically within the earth's crust. The industrial
synthetic quartz growth processes utilize alkaline water solutions confined within autoclaves at
supercritical temperatures (330 °C to 400 °C) and pressures (700 to 2000 atmospheres). The
autoclave is divided into two chambers: the dissolving chamber, containing raw quartz chips at
the higher temperature; the growing chamber, containing cut seeds at the lower temperature
crystal growth in the presence of water of elevated temperature and pressure
[SOURCE: IEC 60758:2016, 3.1 modified – The definition has been shortened.]
3.14
impurity concentration
concentration of impurities relative to silicon atoms
[SOURCE: IEC 60758:2016, 3.12 3.24]
3.15
inclusions
any foreign material within a synthetic quartz crystal, visible by examination of scattered light
from a bright source with the crystal immersed in a refractive index-matching liquid. A
particularly common inclusion is the mineral acmite (sodium iron silicate)
[SOURCE: IEC 60758:2016, 3.9 3.19, modified – Note 1 to entry has been removed.]

– 8 – IEC TS 61994-4-1:2018 RLV © IEC 2018
3.16
infrared absorption coefficient α value
coefficient (referred to as the α value) established by determining the relationship between
absorption of two wavelengths wave numbers
Note 1 to entry: One with wave number is minimal absorption due to OH impurity, the other with high absorption due
to the presence of OH impurities in the crystal lattice. The OH impurity creates mechanical loss in resonators and its
presence is correlated to the presence of other loss-inducting impurities. The α value is a measure of OH
concentration and is correlated with expected mechanical losses due to material impurities.
Note 2 to entry: For the coefficient defined here, the logarithm base 10 is used. The infrared absorption coefficient
value α is determined using the following equation:
1 T
α＝ log
t T
where
α is the infrared absorption coefficient;
ｔ is the thickness of Y-cut sample, in centimetres;
–1 –1
T is the per cent transmission at a wave number of 3 800 cm or 3 979 cm
–1 –1 –1
T is the per cent transmission at a wave number of 3 410 cm , 3 500 cm or 3 585 cm
 
1 T
α = log  
 
t T
 2 
where
is the infrared absorption coefficient;
α
t is the thickness of Y-cut sample, in cm;
–1 –1
is the per cent transmission at a wave number of 3 800 cm or 3 979 cm ;
T
–1 –1
is the per cent transmission at a wave number of 3 500 cm , or 3 585 cm .
T
[SOURCE: IEC 60758:2016, 3.18 3.29]
3.17
internal transmittance
transmittance which does not include loss of surface refraction
[SOURCE: IEC 60758:2016, 3.33, modified – Note 1 to entry has been removed.]
3.18
lumbered synthetic quartz crystal
synthetic quartz crystal whose X- and Z- or Z'- surfaces in the as-grown condition have been
processed flat and parallel by sawing, grinding, lapping, etc., to meet specified dimensions and
orientation
[SOURCE: IEC 60758:2016, 3.19 3.30 ]
3.18
lumbered Y-bar
quartz bars which are lumbered from an as-grown Y-bar
[IEC 60758, 3.19.1]
3.19
lumbered Z-bar
quartz bars which are lumbered from an as-grown Z-bar
[IEC 60758, 3.19.2]
3.19
minimum Z-dimension
minimum distance from seed surface to Z-surface described by Z
min
[SOURCE: IEC 60758:2016, 3.8.1.2 3.18, modified – The reference to Figure 2d has been
removed.]
3.20
orientation of a synthetic quartz crystal
orientation expression of its seed a synthetic quartz crystal with respect to the orthogonal axes
axial system
[SOURCE: IEC 60758:2016, 3.6 3.9 modified – The definition has been made independent of
IEC 60758:2016, 3.7.]
3.21
optical twins
quartz crystal in which regions with the common Z-axis exhibit handedness reversal of the
optical Z-axis
[IEC 60758, 3.17]
– 10 – IEC TS 61994-4-1:2018 RLV © IEC 2018
3.21
orthogonal axial system for of α quartz crystal
the orthogonal axial system is illustrated in figure 1
orthogonal axis system consisting of three axes with a mutually vertical X axis, Y axis and Z
axis
z
z
r
r
z
z
r
r
Y-axis
Y-axis
r r
z
z
X-axis
X-axis
Z-axis
Z-axis
z (minor rhombohedral) z (minor rhombohedral) z (minor rhombohedral)
face face face
z
r r
z
s
s
x x
Z-axis Z-axis
z
z
r r
m
m
m
m
r r
z
z
Y-axis Y-axis
IEC  1704/07
Figure 1 – Orthogonal axial system for quartz
[SOURCE: IEC 60758:2016, 3.7.1 3.10, modified – The reference to Figure 1 at the end of the
definition and Note 1 to entry have been removed.]
3.22
pre-dimensioned bar
any bar of as-grown quartz with dimensions bar whose as-grown dime
...