vacancy

(redirected from Job opening)
Also found in: Dictionary, Thesaurus, Legal, Financial.
Related to Job opening: Job search

vacancy

Physics a defect in a crystalline solid caused by the absence of an atom, ion, or molecule from its position in the crystal lattice

Vacancy

 

(also Schottky defect), a crystal defect owing to the absence of an atom or ion at a crystal-lattice point. Vacancies exist in all crystals, however carefully the crystals are grown. In a real crystal, vacancies arise and vanish as a result of the atoms’ thermal motion. The mechanism of vacancy formation can be represented as the discharge of atoms of the surface layer onto the surface with the subsequent transfer of the surface “holes” developed. Here, in place of bonds with three neighboring atoms, only one bond remains and the other two are broken. Consequently, the work necessary to form a vacancy is equal to the energy of two bonds.

Vacancies migrate randomly in the crystal, changing places with neighboring atoms. The motion of a vacancy is the main cause of the intermixing (self-diffusion) of atoms in a crystal, as well as of the mutual diffusion of contacting crystals. A specific equilibrium concentration of vacancies corresponds to each temperature. The number of vacancies in metal crystals near the melting point reaches 1-2 percent of the number of atoms. For aluminum at room temperature, one vacancy occurs per 1012 atoms, and in metals such as silver and copper, the number of vacancies at room temperature is even smaller. However, despite the small concentration, vacancies substantially influence the physical properties of the crystal: for example, the density decreases and ionic conductance is produced. Vacancies play an important role in heat treatment processes, relaxation of metals, re-crystallization of metals, sintering, and other processes.

REFERENCES

Wert, C, and R. Thomson. Fizika tverdogo tela. Moscow, 1966. (Translated from English.)
Kitell, C. Vvedenie v fiziku tverdogo tela, 2nd ed. Moscow, 1963. (Translated from English.)

vacancy

[′vā·kən·sē]
(solid-state physics)
A defect in the form of an unoccupied lattice position in a crystal.
References in periodicals archive ?
Job openings are a procyclical measure of labor demand.
Construction and extraction workers job openings increase
ASAE Career Opps focuses on job openings in the $30,000-$50,000 annual compensation range in associations and other nonprofit organizations.
Job openings reflected a contraction in labor demand during the most recent recession.
Job openings increase in Top 50 major metros For the second month in a row, job openings increased in all 50 of the major metros.
9%) industries faced the largest decreases in job openings in December.
With nearly two-thirds of all occupation categories experiencing growth in job openings, office and administrative workers (15.
Half of all occupation categories (nine out of 18) experienced growth in job openings this month.
Job openings attributable to the 2010 decennial census are reflected in the JOLTS total nonfarm job openings estimates, while JOLTS total private job openings exclude government job openings.
In addition, the ratio of job openings to job seekers improved in one-third of all major metros, including New York, Los Angeles, Philadelphia and Houston.
The report on Job Openings and Labor Turnover comes after the government said on Friday that employers added 162,000 jobs in July, the fewest in four months.
The ratio of unemployed persons per job opening bottomed in late 2006 to early 2007 and then began to climb through the onset of the December 2007 recession.