Multianvil apparatus

Ibitira 42 Juvinas 29 Yamato-792510 172 multianvil apparatus 2,11,12,21 mosaicism 35,36... 

Figure 1.9. (a) Pressure release in a multianvil apparatus as function of decompression time. The shortest unloading path to ambient pressure takes about 1 s. (b) Fast unloading in a multianvil experiment with starting conditions of2400 0 and 25 GPa... 

Parise JB, Chen J (1997) Studies of ciystalhne solids at high pressure and temperature using the DIA multianvil apparatus. Eur J Solid State Inorg Chem 34 809-821 Parise JB, Coibin DR, Abrams L (1995) Stractural changes upon sorption and desorption of Xe from Cd-exchanged zeolite rho A real-time synchrotron X-ray powder diffraction study. Microporous Mater 4 99-110... 

For a long time fixed-point calibrations were much used in high-pressure measurements, especially with piston-cylinder, belt, and multianvil apparatus, where optical or X-ray access was difficult but electrical wires could be introduced easily. The useful fixed points were related to sharp changes in the electrical resistance at first-order phase transitions. Sharp transitions with minor hysteresis (for instance, in resistance measurements) were considered to be the most useful. For this almost historical reason, some recommended fixed points are given in Table 2.3. 

Wadsleyite ((3-Mg2Si04) is a high-pressure polymorph of forsterite. In wadsleyite deformed at pressures of 14 GPa and 1450 °C, dislocations with [100] Burgers vectors were identified, many in tangles, although creep had caused numerous dislocations to form walls [428]. In wadsleyite synthesized from forsterite in a multianvil apparatus and deformed in compression in another multianvil apparatus at 15-19 GPa and temperatures ranging from room temperature to 1800-2000 °C, TEM and LACBED studies identify [100], <111 >, [010], <101>, and [001] dislocations [85], the lattermost resulting from dislocations reactions, not slip. Wadsleyite is elastically almost isotropic but slip occurs predominately on planes that do not break Si-O bonds (e.g., (010) and (001)) and dislocation dissociation is crucial [86]. 

Two types of high-pressure apparatus are schematically illustrated in Fig. 38. They are the so-called belt-type apparams and the multianvil apparatus, both used in diamond and cBN factories. The belt type is a modified piston-cylinder apparatus. There is also an apparatus called the toroid type, whieh is a modified Bridgman-type anvil apparatus. 

The synthesis of a novel 7-813X4 phase with a cubic spinel structure (see Figure 2.1c) was carried out under high pressure (15 G Pa) and at temperatures above 1920 ° C in a laser-heated diamond cell [22]. Today, many different processing techniques for y-813X4 synthesis are available, the most common being the diamond anvil cell (DAC) synthesis (G. 8erghiou, et al., unpublished results), the multianvil pressure apparatus (MAP) synthesis [23], and the shock synthesis [24]. 

Figure 38 The belt type and the multianvil type of high-pressure apparatus.

---