The above diagrams show qualitative models of the possible positions of H+ and alkali ions in the channels of the quartz lattice, and the corresponding trends in the potential energy curves.  The arrows show the main channels in the quartz lattice - along the z-axis.  It takes much less force to move ions along this channel than along other directions.
	The H+ ion is strongly bound to the O ions; A) and B) show two possible models of H+ in quartz (due to Kats).  As the OH bond is very strong, it is unlikely for a H+ to move along the channel at normal temperatures.  C) to E) show the positions of alkali ions in the channels and the corresponding potentials.  There is a potential well of ~1 eV depth around the Al3+ ion.  Superimposed on that are a series of low potential barriers along the channel that are shown above.  In the Li+ case, only one kind of transition is likely.  In the Na+ and K+ cases, two different kinds of transitions are likely.
	When the Q of a resonator is measured as a function of temperature, defects such as the Al-alkali centers cause acoustic losses as the thermally activated alkalis couple to the oscillating stress field; e.g., the Al-Na+ center causes an acoustic loss peak at 50 K in 5 MHz 5th overtone AT-cut resonators. Above room temperature, the interstitial alkalis are thermally liberated and diffuse along the z-axis which results in Q losses that increase exponentially with temperature. Such Q losses, and the Al-Na+ loss peak are not present in swept crystals (see “Sweeping” later in this chapter).
	Ionizing radiation creates electron-hole pairs that make a transient electrical conductivity increase.  It also liberates ions and allows the ions to move from one potential well to another, thereby changing the elastic constants.  A pulse of radiation thereby causes both a transient and steady-state change in the resonator’s frequency (see radiation effects discussion in chapter 4).
	J. M. Stevels and J. Volger, “Further Experimental Investigations on the Dielectric Losses of Quartz Crystals in Relation to Their Imperfections,” Philips Res. Reports. 17, pp. 283-314, 1962.
	A. Kats, “Hydrogen in Alpha-quartz, Philips Res. Reports. 17, pp. 133-195, 201-279, 1962.
	L. E. Halliburton, J. J. Martin & D. R. Koehler, “Properties of Piezoelectric Materials,” in E. A. Gerber and A. Ballato, Precision Frequency Control, Vol. 1, pp. 1-45, Academic Press, 1985.