How to adapt this code to copy unique values in cells

The following code produces a unique code, however I am unable to make it produce unqiue codes in each of the 6 cells, instead it just copies the same one.

Would really appreciate any advice...

Private Sub CommandButton1_Click()
    Dim strVerificationPD As String
    Dim iPD As Integer
Dim i As Integer

    For iPD = 1 To 8
        If iPD Mod 2 = 0 Then
        

            strVerificationPD = Chr(Int((90 - 65 + 1) * Rnd + 65)) & strVerificationPD
        Else
            strVerificationPD = Int((9 * Rnd) + 1) & strVerificationPD
        End If
Next iPD

For i = 1 To 6


Cells(i, 1).Value = strVerificationPD

Next i
      
End Sub