Quartzs Material Properties

Since this approach does not account for long-range electrostatic potentials present in the extended material, the second approach chosen was the rigid-ion lattice energy minimization technique, widely used in solid-state chemistry. This method is based on the use of electrostatic potentials, as well as Born repulsion and bond-bending potentials parametrized such that computed atom—atom distances and angles and other material properties, such as, for instance, elastic constants, are well reproduced for related materials. In our case, parameters were chosen to fit a-quartz. 

Quartz is abundant and hence inexpensive, relatively hard and chemically inert. Similar to other ceramics, high hardness is a useful property of quartz. Knoop hardness data for a number of ceramic materials including quartz are given in Table 5 [32], The densities of a number of ceramic materials including quartz are given in Table 6 [32],... 

When applying quartz crystal resonators outside Sauerbrey s limitations in the so-called non-gravimetric regime, material properties come into play. The electrical admittance (impedance) of the coated quartz crystal gives access to the determination of material properties of the coating. The crystal cut can again be used for optimization of the sensor performance. If mechanical stability is an issue (e.g., lateral stress induced during the experiment) BT-cut crystals are favorable. 

R. Lucklum, P. Hauptmaim and R.W. Cemosek, Thin Film Material Properties Analysis with Quartz Crystal Resonators, IEEE Intemational Frequency Control Symposium, (2001) 542-50. 

Piezoelectricity, from Greek Klet elv meaning to press, to squeeze [41], is the interplay between mechanical and electrical features of a material or a device. Changing one will impact the other. There are different types of materials that show these properties. Quartz, topaz, and tourmaline minerals human and animal bone tissue different proteins Rochelle salts (sodium, potassium tartrate tetrahydrate) barium titanate, lead zirconate titanate, PZT and the polymer poly (vinyUdene fluoride) (PVDF), are some examples. Piezoelectricity, compared to many other areas of science, was relatively recently discovered, by Jacques and Pierre Curie [42] working with quartz among other minerals. 

The first convincing experiment of this kind was performed by Graham (1972, 1974) whose setup is shown schematically in Fig.6.1. An X-cut a-quartz plate Qi is mounted in an epoxy bed E in an evacuated cylindrical tube. A second X-cut a-quartz plate Q2, mounted on a piston serves as a projectile accelerated by a compressed gas to collide head on with Qi. Careful ahgnment of the two quartz faces and a special ratio of thickness to diameter of Qi insure that upon impact a plane compressive shock wave is generated in Qi. From the impact velocity, measured independently, and from the known material properties the deformation is calculated. The polarization resulting from this deformation by the direct piezoelectric effect is obtained from the electric signal detected from the electrodes of Qi. From measurements at differerrt impact velocities values for the piezoelectric modulus en at different deformations were calculated and fium these a value for em as a measure for the deformation dependence was derived. 

Table 7.2 Material properties of left-handed a-quartz. Convention for the tensor coordinates is after ANSI/IEEE Standard 176-1987...

Table 7.3 Structure of the tensor components for some of the non-linear material properties in quartz (32)...

Crystals are grown by hydrothermal growth method, a- to -Quartz like transition takes place at 950°C in this material. Material properties and their temperature coefficients see Table 7.6. 

Berlinite crystals are very much similar to quartz. Stmctural phase change takes place at the temperature 584°C (Blistanov et al. 1982). For material properties see Table 7.6. Similarly to quartz berlinite crystals undergo a- to jS-phase transition. Crystals are grown by hydrothermal method (Detaint et al. 1985 Motchary and Chvanski 2001) Berlinite crystals exhibit higher electromechanical coupling coefficient than quartz. 

Electromechanical coupling coefficient is higher for LGS than for quartz. Some of the LGS non-linear material coefficients are pubhshed in Sorokin et al. (1996). Temperature coefficients published by different authors show values widely scattered. For material properties and their temperature coefficierrts see Tables 7.7 and 7.8. (Adachi et al. 1999 Bohm et al. 1999, 2000 Ilyaev et al. 1986 Kaminskii et al. 1983a,b, 1984 Onozato et al. 2000 Pisarevskii et al. 1998 Silvestrova et al. 1986, 1987, 1993 Sorokin etal. 1996). 

Poled PVDF films show fenoelectiic behavior clearly demonstrating the polarization reversal in the dielectric Itysteresis curve (Nalwa 1995). Locally created domains ate reported (Giithner and Dransfeld 1992) in scanning force microscopy observations in PVDF. Typical values of the spontaneous polarization are 8-10 X 10 Ccm and of the coercive field 50-100 kVmm . For the material properties see Table 7.17. Uniaxially drawn films are much mote anisotropic in piezoelectric properties. The piezoelectric coefficients are higher than e.g. for quartz crystals, but lower than for PZT ceramics. It is highly desirable to improve the piezoelectric coefficients for the possible applications of polymers. 

In order to operate devices that utilize piezoelectric materials at elevated temperatures, the absence of any structural or electric phase transitions is mandatory. It is for this reason that why, at high temperature, the standard piezoelectric material a-quartz no longer functions because, at 573 °C the piezoelectric a(low)-quartz with symmetry group 32 undergoes a displacive phase transformation to P(high)-quartz with symmetry group 622. > On the other hand, PZT fails to retain its piezoelectric properties at temperatures above 500 °C, because of a ferroelectric-paraelectric phase transformation at the Curie temperature (see Section 8.3.2). 

Properties of materials with quartz sand filler... 

Thus, thermal conductivity is predicted proportional to the square of velocity. The factor Asoiid is controlled only by the solid material properties (minerals). Table 9.16 shows some values for selected minerals. Quartz has a distinctly high magnitude within the most abundant rock-forming minerals, attributed to its high thermal conductivity. Therefore, as tendency for igneous... 

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