Panjarai kristali

Panjarai kristali, shakli fazoiest, ki dar kristallho va jismhoi kristalli botartib joygir shudani atomho, ionho va molekulahoro nishon medihad. Panjarai kristali az yacheykahoi elementarie iborat ast, ki dar se samt davri takror meshavand va sokhti tomi kristallro ba vujud meorand. Yacheykai elemeitari vobas­ta ba simmetriyai kristall shakli parallelepipedi kajkunja yo rostkunja, prizmai kvadrati yo shashkunja, kubro dorad (nig. rasm). Andozahoi tegahoi yacheykai zlementari a, v, s-ro davri ayni menomand.

Panjarai kristali bo digar elementhoi simmet­riya— tirho, hamvoriho, markazi simmetriya niz tavsif meyobad.

Anizotropiyai khosiyati kristallho, shakli hamvori tegahoi onho, doimiyati kunjho va digar qonunhoi kristallografiya!i geometri bo mavjudiyati Panjarai kristjlli sharh doda meshavand. Ba vositai chenkunihoi geometrii kristall buzurgii kunjhoi yacheykai elementari va dar asosi qonuni ratsionaliyati parametrho nisbati davrhoi ayniro yoftan mumkin ast. Andozahoi yacheykaho va joygirshavii atomho yo molekulahoe, ki in sokhtro tashkil medihand, dar har yacheyka bo yorii (rentgenografiya, neytrono­grafiya yo elektronografiya muayyan karda meshavand.

Dar yacheykai elementarii Panjarai kristalli az yak (borai elementhoi khimiyavi) to dahho va sadho (baroi payvasthoi khimiyavi) yo hazorho va hatto millionho (safedaho, virusho) atom joy girifta metavonad. Az in ru davri aynb az yakchand A to sadho va hazor­ho A meshavad.

Panjarai kristali tashkilai statiki (orom) nest. Atomho yo molekulahoe, ki Panjarai kristalliro tashkil mekunand, dar nazdikii holati muvozinat lappida meistand va tabiati in lappish (dinamikam Panjarai kristalli) ba simmetriya, joygirshavii atomho, energiyai bandho vobasta ast. Barobari afzoishi harorat lappishhoi zarraho zurtar meshavand va in hol boisi vayronshavii Panjarai kristalli va ba moe mubaddal shudani modda megardad.

Sokhti voqeii kristall hamesha az skhemai idealie, ki dar mafhumi Panjarai kristali tajassum meyobad, farq mekunad. Az jumla dar kristallhoi voqei hamesha nuqshoi gunogun, ba monandi gashatomho, vakansiyaho, dislokatsiyaho va gayraho mavjudand.