LOW DISLOCATION QUARTZ GROWN ON r / r SEEDS Shvanskiy P.P., Motchanyy A.I., Dikk E.V., Solovyeva O.V., Arkhipov М.А.,Orlov O.M. Shvanskiy P.P., Motchanyy A.I., Dikk E.V., Solovyeva O.V., Arkhipov М.А.,Orlov O.M. - Russian Research Institute for the Synthesis of Materials (VNIISIMS), - Russian Research Institute for the Synthesis of Materials (VNIISIMS), - Quartz Palitra Ltd. - Quartz Palitra Ltd. 1, Institutskaya, Alexandrov, Vladimir Region , Russia 1, Institutskaya, Alexandrov, Vladimir Region , Russia - FONON Ltd. - FONON Ltd. 20, Krasnobogatirskay, Moscow, Russia 20, Krasnobogatirskay, Moscow, Russia

1. Introduction The modern technology of growing synthetic quartz is lead up to high perfection and allows to create crystals meeting the most refined requirements. However, practice shows that not all existing piezoquartz crystals can be used for manufacturing high-frequency resonators.The modern technology of growing synthetic quartz is lead up to high perfection and allows to create crystals meeting the most refined requirements. However, practice shows that not all existing piezoquartz crystals can be used for manufacturing high-frequency resonators. Serially produced synthetic quartz of z, x, r - directions not always can be used for manufacturing tiny piezoelectric products, as they contain a lot of structural defects. One of the difficulties of quartz cultivation is the growth of crystals with the minimal contents of dislocations and channels.Serially produced synthetic quartz of z, x, r - directions not always can be used for manufacturing tiny piezoelectric products, as they contain a lot of structural defects. One of the difficulties of quartz cultivation is the growth of crystals with the minimal contents of dislocations and channels. In this report the description of an up-to-date way to grow low dislocation quartz crystals that are intended for manufacturing prospective devices is presented.In this report the description of an up-to-date way to grow low dislocation quartz crystals that are intended for manufacturing prospective devices is presented.

Quartz crystals grown on plate seeds of zx, zy, rx, ry`orientations

rу'- crystal X-ray topogram, (11-20)–reflex rу'- crystal X-ray topogram, (11-20)–reflex

2. Experimental The new type of seed material assumes the use of rod form orientated in length along [10-11] direction. These crystals have received the name r/r-bar crystals.The new type of seed material assumes the use of rod form orientated in length along [10-11] direction. These crystals have received the name r/r-bar crystals. The axis of a rod seed is located at an angle 57° 6 ' to the axis Z in ZY plane. Morphologically this direction corresponds to an edge between two adjacent sides of a negative rhombohedron, which are connectedby axis of the third order.The axis of a rod seed is located at an angle 57° 6 ' to the axis Z in ZY plane. Morphologically this direction corresponds to an edge between two adjacent sides of a negative rhombohedron, which are connectedby axis of the third order.

Diagram of r/r seed disposition m R r s x R r y x z x y r

Rod seeds of r/r orientation. On the basis of given data rod seeds (5.0х х2.0 mm) of square section and with a length up to 350 mm along Y' axis were made.On the basis of given data rod seeds (5.0х х2.0 mm) of square section and with a length up to 350 mm along Y' axis were made.

Quartz crystals of r/r orientation Quartz crystals of r/r orientation For the realization of experiments we used high pressure autoclaves with the following characteristics: - capacity 24 liters, - pressure MPa - temperature up to 500°C The crystallization was carried out using solutions of sodium hydroxide (4%). The common area of seeds was 9-11 cm²/liter and constant in all cycles. These crystals were grown at the interval of temperatures °C and pressure 110 – 130 MPa.

SEED ORIENTATIONS Two 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) b)

External form of r-bar crystals 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 side as a function of the temperature gradient of crystallization (Т cryst. = 355 ºС, 4% NaOH) Growth rate of the quartz side as a function of the temperature gradient of crystallization (Т cryst. = 355 º С, 4% NaOH)  V ( + x) ○ V (r) Δ V (-x ) V+x ≥ Vr > V-xV+x ≥ Vr > V-x

Т cryst. = ºС Т cryst. = º С ΔT=10-12 ºС V + x > V r Vr = 0.10 – 0.12 mm/day V r ≤ V + x Vr = 0.17 – 0.20 mm/day ΔT=16-18 ºС

Vr > V+x > V-xVr > V+x > V-x V+x > Vr > V-xV+x > Vr > V-x Т cryst = 336 – 338 º С ΔT=16 º С Т cryst = 350 – 355 º С ΔT= 17 º С Crystallization temperature and growth rates V+x, Vr, and V-x.

r/r - crystal and AT-cut r/r - crystal and AT-cut

Plates of АТ- cut Integral gamma-irradiation dose - 5х10 6 R

X-ray topogram АТ-cut ( reflex) Distribution of dislocations in the volume of pyramyd according to X- ray topogram reaches from 1 to 10 pcs/cm 2

Plate of АТ-cut from r-bar crystal

r-bar crystals grown in the vessel of 24 liter and 1500 liter

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