List of Symbols¶
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| Symbol | Description |
|---|---|
| Ain | absorbance \(A_{in}=-\ln[I/I_0]=-\ln\tau_{in}\) |
| Am | measured absorbance \(A_{m}=-\ln[I_{m}/I_0]=-\ln\tau_{m}\) where \(I_{m}\) is the actual intensity of transmitted light (resulted from both absorption in a medium and reflection from sample surfaces) |
| A.P. | Annealing Point |
| a | thermal diffusivity |
| B | stress-optic coefficient |
| b | thickness of a dissolved layer (for studies of chemical durability); thickness of a crystallized layer (for studies of crystallization) |
| C | heat capacity |
| Cp | heat capacity at constant pressure |
| Cv | heat capacity at constant volume |
| cl | longitudinal sound velocity |
| ct | transverse sound velocity |
| D | Diffusion coefficient |
| Din | 1. coefficient of interdiffusion 2. optical density \(D_{in}=-\log[I/I_0]=-\log\tau_{in}\) |
| Dm | measured optical density \(D_{m}=-\log[I_{m}/I_0]=-\log\tau_{m}\) where \(I_{m}\) is the actual intensity of transmitted light (resulted from both absorption in a medium and reflection from sample surfaces) |
| DTA | differential thermal analysis |
| d | density |
| dl | thickness of crystallized layer |
| E | 1. Young's modulus 2. activation energy of a transport process |
| F | Weibull probability (see Weibull distribution function) |
| f | frequency |
| fl | frequency of longitudinal oscillations |
| ft | frequency of transverse oscillations |
| G | shear modulus |
| H | 1. microhardness 2. enthalpy |
| l | load |
| I0 | nucleation rate |
| K | 1. bulk modulus 2. coefficient of Gas permeation |
| KIC | fracture toughness |
| k | absorption coefficient \(k=A_{in}/d\) where \(d\) is the thickness of a measured sample |
| L | 1. length 2. elastic constant (see Elastic properties) |
| L.P. | Littleton Point |
| Mg | dilatometric Softening Temperature |
| N | number of nucleated crystals |
| n | 1. refractive index; usually appears with a subscript (Fraunhofer's symbol) indicating the corresponding wavelength; the difference nF – nC is taken as mean dispersion 2. amount of the dissolved glass (or of a glass component) |
| P | 1. Pressure 2. pressure of evaporated gas |
| p | property |
| Q-1 | characteristics of internal friction equal to the ratio of loss modulus G to storage modulus G |
| \(Q^{-1}_{l}\) | the same for longitudinal waves |
| \(Q^{-1}_{t}\) | the same for transverse waves |
| S | gas solubility coefficient |
| SA/V | Surface-area-to-volume ratio. Ratio of surface area of glass sample and volume of surrounding solution (for studies of chemical durability) |
| S.P. | Strain Point |
| T | temperature |
| \(T_{i}(\log\eta=i)\) | temperature corresponding to viscosity logarithm value equal to \(i\) |
| Tc | crystallization temperature (temperature of a peak on DTA curve resulting from a crystallization process) |
| Tf | fictive temperature |
| Tg | glass transition temperature |
| \(T_{g}^{+}\) | glass transition temperature determined in the course of glass heating |
| Tg1 | glass transition temperature of low-viscosity phase of a phase separated substance |
| Tg2 | glass transition temperature of high-viscosity phase of a phase separated substance |
| Th | high-temperature borderline of annealing range |
| Tl | low-temperature borderline of annealing range |
| Tliq | liquidus temperature |
| Tm | melting temperature (temperature of the end of crystal melting process in the course of heating a sample) |
| Tmax | maximum crystal growth temperature |
| Tn | nucleation temperature |
| Troom | room temperature |
| Tx | onset crystallization temperature (temperature of the beginning of crystallization determined by DTA curve) |
| \(tan\delta\) | tangent of loss angle (for electrical, acoustical, and another kinds of sinusoidal excitation) |
| TEC | thermal expansion coefficient |
| TK-100 | temperature corresponding to specific electrical resistivity of a glass equal to \(10^{8} Ohm \cdot cm\) |
| TMA | thermomechanical analyzer |
| t | time |
| tind | induction period (in the course of nucleation) |
| V | volume |
| v | 1. velocity of a process (rate of dissolution, rate of crystal growth etc) 2. molar volume |
| vmax | maximum crystal growth rate |
| \(v_{\alpha}\) | critical cooling rates |
| VFT | Vogel-Fulcher-Tammann equation describing temperature dependence of viscosity \(\log\eta=A+B/(T-T_{0})\) where A, B, and \(T_{0}\) are constants |
| \(\alpha\) | 1. linear thermal expansion coefficient 2. absorption coefficient \(\alpha=D_{in}/d\) |
| \(\alpha_{i}\) | instantaneous linear thermal expansion coefficient of a substance |
| \(\alpha_{l}\) | 1. linear thermal expansion coefficient of a substance in a liquid state 2. absorption coefficient for longitudinal acoustic waves |
| \(\alpha_{s}\) | structural linear thermal expansion coefficient (LTEC) of a substance |
| \(\alpha_{t}\) | absorption coefficient for transverse acoustic waves |
| \(\beta\) | volume thermal expansion coefficient |
| \(\Delta\) | error of measurements |
| \(\Delta\) Cp | difference in heat capacity of liquid and glassy state in the vicinity of glass transition region |
| \(\Delta\) Hc | heat of crystallization |
| \(\Delta\) Hs | heat of solution |
| \(\Delta\) tte | thermal endurance |
| \(\Delta\varepsilon\) | \(\varepsilon_{0}-\varepsilon_{\infty}\) |
| \(\delta\) | dielectric loss angle |
| \(\delta p\) | change in property p |
| \(\varepsilon_{d}\) | extinction coefficient calculated according to the equation \(\varepsilon_{d}=D/cd\) where \(D\) is the optical density, \(c\) is the concentration of the absorbing component, and \(d\) is the thickness of the sample |
| \(\varepsilon_{n}\) | extinction coefficient calculated according to the equation \(\varepsilon_{n}=A/cd\) where \(A\) is the absorbance, \(c\) is the concentration of the absorbing component, and \(d\) is the thickness of the sample |
| \(\varepsilon '\) | real part of the complex permittivity, also called relative permittivity or dielectric constant |
| \(\varepsilon '_{0}\) | relative permittivity for \(f\rightarrow0\) |
| \(\varepsilon '_{\infty}\) | relative permittivity for \(f \rightarrow \infty\) or \(T \rightarrow 0\) |
| \(\varepsilon ''\) | loss coefficient or dielectric loss \(\varepsilon ''=\varepsilon ' \cdot tan\delta\) |
| \(\eta\) | viscosity |
| \(\kappa\) | specific electrical conductivity |
| \(\kappa_{m}\) | molar electrical conductivity |
| \(\kappa_{s}\) | specific surface electrical conductivity |
| \(\lambda\) | 1. thermal conductivity 2. logarithmic damping coefficient of internal friction 3. wave length |
| \(\mu\) | 1. Poisson's ratio 2. ionic mobility |
| \(\mu_{im}\) | imaginary Poisson's ratio (in cases of measurements for glass fibers) |
| \(\nu\) | 1. dispersion coefficient 2. frequency of electromagnetic oscillations 3. reciprocal centimeters (in optical spectra) |
| \(\rho\) | specific electrical resistivity |
| \(\rho_{s}\) | specific surface electrical resistivity |
| \(\sigma\) | 1. surface tension 2. strength |
| \(\sigma_{b}\) | bending strength |
| \(\sigma_{c}\) | compression strength |
| \(\sigma_{imp}\) | impact strength |
| \(\sigma_{t}\) | tensile strength |
| \(\tau\) | 1. relaxation time 2. induction period (characteristics of nucleation ability; see crystallization) 3. optical transmission |
| \(\tau_{in}\) | intrinsic optical transmission \(\tau_{in}=I/I_{0}\) where \(I\) is the intensity of light transmitted through a sample in circumstances when there are no losses due to reflection from glass surfaces |
| \(\tau_{m}\) | measured optical transmission of a sample (it includes losses for reflection) |
| \(\chi\) | 1. compressibility 2. magnetic susceptibility |