LOW DISLOCATION LOW DISLOCATION QUARTZ GROWN QUARTZ GROWN

ON ON rr//r r SEEDSSEEDS Shvanskiy P.P., Motchanyy A.I., Dikk E.V., Shvanskiy P.P., Motchanyy A.I., Dikk E.V., Solovyeva O.V., Solovyeva O.V., Arkhipov Arkhipov М.А.М.А.,,Orlov O.M.Orlov O.M.

- - Russian Research Institute for the Synthesis of Russian Research Institute for the Synthesis of Materials (VNIISIMS),Materials (VNIISIMS), - - Quartz Palitra Ltd.Quartz Palitra Ltd. 1, Institutskaya, Alexandrov, Vladimir Region 1, Institutskaya, Alexandrov, Vladimir Region 601650, Russia601650, Russia - - FONON Ltd.FONON Ltd. 20, Krasnobogatirskay, Moscow, Russia 20, Krasnobogatirskay, Moscow, Russia

1. I1. Introductionntroduction• The modern technology of growing synthetic quartz The modern technology of growing synthetic quartz

is lead up to high perfection and allows to create is lead up to high perfection and allows to create crystals meeting the most refined requirements. crystals meeting the most refined requirements. However, practice shows that not all existing However, practice shows that not all existing piezoquartz crystals can be used for manufacturing piezoquartz crystals can be used for manufacturing high-frequency resonators.high-frequency resonators.

• Serially produced synthetic quartz of z, x, r - Serially produced synthetic quartz of z, x, r - directions not always can be used for manufacturing directions not always can be used for manufacturing tiny piezoelectric products, as they contain a lot of tiny piezoelectric products, as they contain a lot of structural defects. One of the difficulties of quartz structural defects. One of the difficulties of quartz cultivation is the growth of crystals with the minimal cultivation is the growth of crystals with the minimal contents of dislocations and channels.contents of dislocations and channels.

• In this report the description of an up-to-date way to In this report the description of an up-to-date way to grow low dislocation quartz crystals that are grow low dislocation quartz crystals that are intended for manufacturing prospective devices is intended for manufacturing prospective devices is presented.presented.

Quartz crystals grown on plate Quartz crystals grown on plate seeds of zx, zy, rx, seeds of zx, zy, rx,

ryry`̀orientationsorientations

rrу'- у'- crystalcrystalX-ray topogram, (11-20)–X-ray topogram, (11-20)–

reflexreflex

2. E2. Experimentalxperimental

• The new type of seed material assumes the The new type of seed material assumes the use of rod form orientated in length along use of rod form orientated in length along [[10-10-1111]] direction. These crystals have received the direction. These crystals have received the name r/r-bar crystals. name r/r-bar crystals.

• The axis of a rod seed is located at an angle The axis of a rod seed is located at an angle 57° 6 ' to the axis Z in ZY plane. 57° 6 ' to the axis Z in ZY plane. Morphologically this direction corresponds to Morphologically this direction corresponds to an edge between two adjacent sides of a an edge between two adjacent sides of a negative rhombohedron, which are negative rhombohedron, which are connectedby axis of the third order.connectedby axis of the third order.

Diagram of r/r seed Diagram of r/r seed dispositiondisposition

m

R

r

sx

R

r

y

x

z

x

y

r

Rod seeds ofRod seeds of r/r r/r orientationorientation..

• On On the the basisbasis of given data rod seeds of given data rod seeds ((5.05.0хх5.0 -5.0 -22.0.0х2.х2.00 mm) of square mm) of square section and with a length up to 350 section and with a length up to 350 mm along Y' axis were made.mm along Y' axis were made.

Quartz crystals ofQuartz crystals of r/r r/r orientationorientation

• • For the realization of experiments we For the realization of experiments we used high pressure autoclaves with used high pressure autoclaves with the following characteristics: the following characteristics:

- - capacity 24 liters, capacity 24 liters, - pressure 100-150 MPa- pressure 100-150 MPa - temperature up to 500°C- temperature up to 500°C The crystallization was carried out The crystallization was carried out

using solutions of using solutions of sodium hydroxide sodium hydroxide (4%).(4%). The common area of seeds was The common area of seeds was 9-11 cm²/liter and constant in all 9-11 cm²/liter and constant in all cycles. cycles.

• These crystals were grown at the These crystals were grown at the interval of temperatures 3interval of temperatures 33535 - 360°C - 360°C and pressure 110and pressure 110 –– 130 MPa.130 MPa.

SEED ORIENTATIONSSEED ORIENTATIONSTwo major seed orientations are used for r/r crystals growth.

а) faceted by the faces of positive and negative trigonal prism and sharp rhombohedrons;

b) faceted by the faces of main small rhombohedron.

а)а) b)b)

External form of r-bar External form of r-bar crystalscrystals

r – (1-1.1), (01.1) (0-1.1), (-11.-1)

(-x) – (1-2.0)

R – {10.1}

m – { 10.1}

Growth rate of the quartz sideGrowth rate of the quartz side as a as a function of the temperature function of the temperature gradient of crystallization gradient of crystallization

((ТТcryst.cryst. = 355 º = 355 º СС, 4% NaOH, 4% NaOH))

V(+x)

○ V(r)

Δ V(-x)

•VV++xx ≥ ≥ VrVr > > VV--xx

Т Т cryst.cryst. = 350 - 355 º = 350 - 355 º СС

ΔΔT=T=10-12 10-12 ººСС

VV++xx > > VVrr

VrVr = 0.10 – 0.12 mm/day = 0.10 – 0.12 mm/day

VVrr ≤ ≤ VV++xx

VrVr = 0.17 – 0.20 = 0.17 – 0.20 mm/daymm/day

ΔΔT=T=16-18 16-18 ººСС

•VrVr > > VV++xx > > VV--xx •VV++xx > > VrVr > > VV--xx

Т Т crystcryst = 336 – 338 = 336 – 338 ºº ССΔΔT=T=16 16 ººСС

Т Т crystcryst = 350 – 355 = 350 – 355 ºº ССΔΔT=T= 17 17 ºº СС

Crystallization temperature and growth rates

V+x , Vr, and V-x.

r/rr/r - crystal - crystal andand AT-cutAT-cut

Plates ofPlates of АТ АТ- cut- cutIntegral gamma-irradiation dose Integral gamma-irradiation dose - 5х10- 5х1066 RR

X-ray topogram АТX-ray topogram АТ-cut-cut(01-11 - (01-11 - reflexreflex))

• Distribution of Distribution of dislocations in dislocations in the volume of the volume of pyramyd pyramyd < r > < r > according to X-according to X-ray topogram ray topogram reaches from 1 reaches from 1 to 10 pcs/cmto 10 pcs/cm22

Plate of Plate of АТАТ-cut from-cut from r-bar r-bar crystalcrystal

r-bar crystalsr-bar crystals grown in the grown in the vessel ofvessel of

24 liter and 1500 liter24 liter and 1500 liter

ConclusionConclusion

• The research work has resulted in The research work has resulted in creation of a new type of piezoquartz creation of a new type of piezoquartz crystals crystals – r/r– r/r orientated crystals that are orientated crystals that are prolonged along Y-axis up to 360 mm. It prolonged along Y-axis up to 360 mm. It was found out that r/r crystals are was found out that r/r crystals are growing in size mainly due to the growth growing in size mainly due to the growth of small rhombohedrons faces of small rhombohedrons faces - (01-11). - (01-11). The crystals are highly suitable for making The crystals are highly suitable for making AT-cut bars used for mass production of AT-cut bars used for mass production of ultra-high frequency resonators.ultra-high frequency resonators.